Handheld squeezable exercising devices are well known. These devices can generally be categorized into two groups: those with high compressibility and those with high resiliency. Devices with high compressibility are typified by putties and have poor or moderate resiliency. Griffin, U.S. Pat. No. 3,413,243, discloses a partially compressible ball consisting of a blend of various rubbers containing interconnected air cells. Kaiser, U.S. Pat. No. 3,677,997, and Christy, U.S. Pat. No. 5,319,021, disclose bouncing putties based upon organosiloxane-boron compound mixtures. Scatterday, U.S. Pat. No. 5,190,504, discloses a semi-resilient rubber-coated ball with a non-resilient particulate core.
Devices with high resiliency are exemplified by rubber balls or spring-loaded device. Often these devices cannot be compressed to the extent that the user can exercise using a full range of motion, i.e., moving the fingers from a substantially open position to a position where the fingers are only a few millimeters from the palm. In addition, these devices provide an increasing return force as the device is further and further compressed. Osher et al. (U.S. Pat. No. 5,026,054), for example, teaches a resilient, deformable ball consisting of a plasticized polymeric core and a flexible polymer shell. Biddlecombe (U.S. Pat. No. 4,840,370) teaches a convex block of resilient material such as foamed polyurethane with controllable resistance using multiple layers of polyurethane. Chen, U.S. Pat Nos. 4,618,213 and 4,369,234, disclose resilient balls made with poly(styrene-ethlylene-butylene-styrene) triblock copolymers and plasticizing oil; however, the oil tends to leach out onto the hands of the user, creating a mess and eventually causing the ball to become brittle.
Polyurethane compositions are also known. Brauer, U.S. Pat. No. 4,008,197, discloses a polyurethane composition containing 8 to 20 parts urethane polymer, 60 to 75 parts mineral oil, and 10 to 25 parts coupling agent. Jamison, U.S. Pat. No. 4,623,472, discloses a composition of isocyanate, polyol, catalyst and oil, where the oil constitutes at least 30 percent.
Thus, despite the numerous variations within the known art, a need still exists for a handheld exercising device that provides high compressibility, high resiliency and constant resistance throughout its range of compression and yet which also provides an appealing feel. The composition of the present invention can be shaped into a device that provides a compressibility, resiliency and feel that is well suited for exercising the hand, wrist and arm of the user.